Comparative Evaluation of Three Enzyme-Linked Immunosorbent Assay Test Kits and RPR for Determination of Antibodies to Syphilis in Blood Donors

Abstract

Abstract: Syphilis is a chronic disease, caused by the spirochete: Treponema pallidum: subspecies
pallidum. Syphilis can transmit via blood transfusion thus donated blood have to be screened for
syphilitic infection before giving to the patients. The serological tests for syphilis fall into two categories:
"non-treponemal tests" which are non-specific tests including Venereal Disease Research Laboratory test
(VDRL) and Rapid Plasma Reagin (RPR) and "Treponemal tests" which are specific tests for syphilis such
as Treponema pallidum heamagglutination (TPHA), Fluorescent Treponema Antibody absorption (FTA-
ABS). The perfect test for syphilis has not yet been developed. RPR is currently used for syphilisscreening
in donated blood for decades. Now there are enzyme link immunosorbent assay (ELISA) for Syphilis
screening tests developed by many company, which are proper and convenient for screening of donated
blood. The new technology must be evaluated for performance in intended use compare with the current
technology and the reference one. Objective: To evaluate the sensitivity and specificityof three different
ELISA test kits in comparison to rapid plasma reagin (RPR) assay which is currently used for syphilis
screenina in donated blood. Materials/Method: One thousand two hundred and fiftv unselected donors'serum samples and 206 TPHA positive serum samples from National Blood Centre, Thai Red Cross
Society were included in this study. All samples were tested with three different ELISA test kits, which
were Bioelisa SYPHALIS (Bioelisa), Ice Syphilis and SYPHILIS EIA 480 (New Market EIA) compared to
SyphScreen'M-RPR. TPHA was used as reference test. All methods were performed according to the
manufacturer instructions. Results: the sensitivity of ELISA test kits: Bioelisa, Ice Syphilis and New Market
EIA were 92.72%, 98.06% and 98.06% respectively while the sensitivity of RPR was 75.24%. The specificity
of Bioelisa,Ice Syphilis, New Market EIA and RPR were 99.18%, 99.51%, 99.92%, and 99.75% respectively.
Conclusion: It was found that all three ELISA test kits had higher sensitivity and comparable specificity
to RPR. Therefore, ELISA test kits are suitable for syphilis screening in donated blood.